1. Field of the Invention
This invention relates generally to filter devices, and especially to filters of small micron particle blocking capability for use with intravenous drip chambers.
2. Description of the Prior Art
A common problem with known filters of conventional type for use with intravenous drip chambers is that they have a tendency for the filter membrane to dislodge and/or move out of the proper filtering position. This can either block fluid flow and/or permit small sized particulates to pass. In either case, the result is very undesirable.
Another problem with known type filter devices is that they are relatively complicated to manufacture, and not always leakproof, and fail to properly block small particulates, especially of approximately 15 micron size.
The prior art U.S. Pat. No. 3,658,183 discloses a filter having an upper and lower housing element, both being provided with mating sections to facilitate locking same together. A filter material 10 is adapted to rest on the marginal edges 16 of the lower filter element. After being positioned thereon, the lower element is pushed into engagement with the upper element, and the flexible portions 23 flex sufficiently to allow the lowermost element to be pushed into firm contact with the upper element and to be locked in position, as shown in FIG. 2 of the patent drawings. However, this device does not have a single seat inside an adapter for positioning and retaining a filter ring with the filter ring having an integral filter membrane therewith. Also, the device is not intended for a permanent assembly, but the mating parts are disassembleable so that the filter element can be removed. Also, the membrane is supported by radially spaced raised annular ribs or rings for providing intermediate support of the relatively large filter element. Furthermore, the rings are divided into arcuate sections by radially extending fluid flow channels. This structure of a series of spaced ribs together with traverse slots for fluid flow is not present in the present invention. Also, the method of assembly and making of the present device is substantially different from that of this patent.
Neither this patent nor any other known prior art devices offer the new and novel features of the present invention.